Marshall was called up by the Diamondbacks in May and never looked back, striking out more than a batter per inning in his first taste of the big leagues. He became an asset in leagues that reward holds, piling up 19 over 57 appearances and proving capable of mitigating the effects of hitter-friendly Chase Field by inducing grounders at a 60.7% clip. Marshall has plenty of velocity on his fastball (average 93.9 mph) and he can use his secondary pitches -- a curveball and changeup -- to keep hitters guessing (13.9% swinging-strike rate). He also showed progress in the second half, shaving more than a run from his ERA (second-half 2.03 ERA; 31:8 K:BB in 26.2 innings). With improvement against lefties, Marshall may be a sleeper to eventually close, but he'll have a prominent role in the Arizona bullpen regardless of whether that opportunity comes in 2015.